Analytical experiments and observations on lac

Abstract

A brief historical account of the substance here treated of is prefixed to this paper. Though long in use, especially in India, yet, except what we have lately learnt from Mr. Kerr and Mr. Saunders, few inquiries have hitherto been made concerning its mode of production, first discovery, its nature and relative properties. We now know that it is the nidus or comb of the insect called Coccus, or Chermes Lacca, deposited on branches of certain species of Mimosa and other plants; and that the kingdom of Assam furnishes it in the greatest quantity. There are four sorts of it:—1. The stick lac, being the substance or comb in its natural state, incrusting small branches or twigs. 2. Seed lac, or the same substance granulated, but probably prepared in some manner, it being deprived of a great part of its colouring matter. 3. Lump lac, formed from seed lac, liquefied by fire, and formed into cakes. And, 4. Shell lac, being the original comb, liquefied in water, strained through a cotton cloth, and spread upon a junk of a plantain-tree so as to form thin transparent laminæ: this kind contains the least of the tinging substance, as may well be expected from the mode in which it is prepared. Among the chemists who have hitherto analysed this substance, none deserve notice except M. Geoffroy; but our author’s present labours render his investigations of little or no avail.